Don't skip CI builds for Omnibus and CNG
When tagging releases using the API, we would add ci skip
to the
commit message when updating version files. This would prevent CNG and
Omnibus tag pipelines from running, which are necessary to build the
packages.
To work around this, we disable CI build skipping by default. Only for releases where we don't care about the CI status (e.g. GitLab CE and Gitaly tags) do we skip the CI builds.
A drawback is that we run some additional pipelines on our various mirrors when creating tags. This however is something we could take care of with better CI configuration files, so we for example don't run tests for tags pushed to security mirrors.